export default {
    bind(el, binding, vnode) {
        const minWidth = 400
        const minHeight = 300
        const maxWidth = document.body.clientWidth
        const dialogHeaderEl = el.querySelector('.el-dialog__header')
        const dragDom = el.querySelector('.el-dialog')
        dialogHeaderEl.style.cssText += ';cursor:move;'
        dragDom.style.cssText += ';top:0px;'

        // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
        const getStyle = (function () {
            if (window.document.currentStyle) {
                return (dom, attr) => dom.currentStyle[attr]
            } else {
                return (dom, attr) => getComputedStyle(dom, false)[attr]
            }
        })()

        dialogHeaderEl.onmousedown = (e) => {
            // 鼠标按下，计算当前元素距离可视区的距离
            const disX = e.clientX - dialogHeaderEl.offsetLeft
            const disY = e.clientY - dialogHeaderEl.offsetTop

            const dragDomWidth = dragDom.offsetWidth
            const dragDomheight = dragDom.offsetHeight

            const screenWidth = document.body.clientWidth
            const screenHeight = document.body.clientHeight

            const minDragDomLeft = dragDom.offsetLeft
            const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth

            const minDragDomTop = dragDom.offsetTop
            const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight

            // 获取到的值带px 正则匹配替换
            let styL = getStyle(dragDom, 'left')
            let styT = getStyle(dragDom, 'top')

            if (styL.includes('%')) {
                styL = +document.body.clientWidth * (+styL.replace(/%/g, '') / 100)
                styT = +document.body.clientHeight * (+styT.replace(/%/g, '') / 100)
            } else {
                styL = +styL.replace(/\px/g, '')
                styT = +styT.replace(/\px/g, '')
            }

            document.onmousemove = function (e) {
                // 通过事件委托，计算移动的距离
                let left = e.clientX - disX
                let top = e.clientY - disY

                // 边界处理
                if (-(left) > minDragDomLeft) {
                    left = -minDragDomLeft
                } else if (left > maxDragDomLeft) {
                    left = maxDragDomLeft
                }

                if (-(top) > minDragDomTop) {
                    top = -minDragDomTop
                } else if (top > maxDragDomTop) {
                    top = maxDragDomTop
                }

                // 移动当前元素
                dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`

                // emit onDrag event
                vnode.child.$emit('dragDialog')
            }

            document.onmouseup = function () {
                document.onmousemove = null
                document.onmouseup = null
            }
        }

        dragDom.onmousemove = function (e) {
            const moveE = e
            if (!(el.scrollTop + e.clientY > dragDom.offsetTop + dragDom.clientHeight - 10) &&
                (e.clientX > dragDom.offsetLeft + dragDom.clientWidth - 10)) {
                dragDom.style.cursor = 'w-resize'
            } else if ((el.scrollTop + e.clientY > dragDom.offsetTop + dragDom.clientHeight - 10) &&
                !(e.clientX > dragDom.offsetLeft + dragDom.clientWidth - 10)) {
                dragDom.style.cursor = 's-resize'
            } else if ((el.scrollTop + e.clientY > dragDom.offsetTop + dragDom.clientHeight - 10) &&
                (e.clientX > dragDom.offsetLeft + dragDom.clientWidth - 10)) {
                dragDom.style.cursor = 'se-resize'
            } else {
                dragDom.style.cursor = 'default'
                dragDom.onmousedown = null
            }
            dragDom.onmousedown = (e) => {
                const clientX = e.clientX
                const clientY = e.clientY
                const elW = dragDom.clientWidth
                const elH = dragDom.clientHeight
                const EloffsetLeft = dragDom.offsetLeft
                const EloffsetTop = dragDom.offsetTop
                dragDom.style.userSelect = 'none'
                const ELscrollTop = el.scrollTop
                // 判断点击的位置是不是为头部
                if (clientX > EloffsetLeft && clientX < EloffsetLeft + elW && clientY > EloffsetTop && clientY < EloffsetTop + 100) {
                    // 如果是头部在此就不做任何动作，以上有绑定dialogHeaderEl.onmousedown = moveDown;
                } else {
                    document.onmousemove = function (e) {
                        e.preventDefault() // 移动时禁用默认事件
                        // 右侧鼠标拖拽位置
                        if (clientX > EloffsetLeft + elW - 10 && clientX < EloffsetLeft + elW) {
                            // 往左拖拽
                            if (clientX > e.clientX) {
                                if (dragDom.clientWidth < minWidth) {

                                } else {
                                    dragDom.style.width = elW - (clientX - e.clientX) * 2 + 'px'
                                }
                            }
                            // 往右拖拽
                            if (clientX < e.clientX) {
                                if (dragDom.clientWidth >= maxWidth) {
                                    dragDom.style.width = maxWidth;
                                } else {
                                    dragDom.style.width = elW + (e.clientX - clientX) * 2 + 'px'
                                }
                            }
                        }
                        // 底部鼠标拖拽位置
                        if (ELscrollTop + clientY > EloffsetTop + elH - 20 && ELscrollTop + clientY < EloffsetTop + elH) {
                            // 往上拖拽
                            if (clientY > e.clientY) {
                                if (dragDom.clientHeight < minHeight) {

                                } else {
                                    dragDom.style.height = elH - (clientY - e.clientY) + 'px'
                                }
                            }
                            // 往下拖拽
                            if (clientY < e.clientY) {
                                dragDom.style.height = elH + (e.clientY - clientY) + 'px'
                            }
                        }
                    }
                    // 拉伸结束
                    document.onmouseup = function (e) {
                        document.onmousemove = null
                        document.onmouseup = null
                    }
                }
            }
        }
    }
}
